In any racing self-discipline, as competitors will increase so do the speeds. In accordance with Issue’s engineering director, Graham Shrive, this elevated competitors in gravel racing is elevating speeds to the purpose the place aerodynamic optimisation can supply an actual benefit. That’s an attention-grabbing tidbit from a well-qualified engineer who beforehand claimed that aerodynamics in gravel was overrated.
With these growing speeds and renewed perspective, the premium carbon bike producer has launched the Ostro Gravel, an aero gravel race bike that’s been seen doing the rounds in large American occasions this 12 months. And with Ostro within the identify, it unsurprisingly seems like the corporate’s well-rounded aero highway race bike.
Constructed to be quick in one-day races and slightly versatile past that, the Ostro Gravel combines fashionable geometry with an aerodynamic design that’s stated to be designed across the decrease velocity of using off-road. Add in clearance for 45 mm rubber, UCI certification for highway racing use, and a surprisingly robust-but-light building and that is one intriguing gravel bike (which may very well be mistaken for a highway bike) that stands amongst a shortlist of roughly comparable bikes such because the BMC Kaius, 3T Exploro RaceMax, Cervelo Aspero 5, and never many extra.
Over the previous few weeks, I’ve been placing some miles on the Ostro Gravel, on and off the highway. This in-depth evaluate covers what Issue has to say in regards to the new Ostro Gravel and what I’ve to say about it, too.
- What: An aerodynamically optimised gravel race bike.
- Key particulars: Built-in design with one-piece handlebar/stem, clearance for 700 x 45 mm rubber, T47 Assymetric backside bracket, UCI certification.
- Weight: 913 g (painted 54 cm body), 490 g (uncut fork), 8.05 kg (as examined, with out pedals).
- Worth: US$5,500 / €5,450 / £4,730 (frameset with handlebar and extra), US$9,800 / €9,710 / £8,430 (full, as examined).
- Highs:Spectacular stiffness, good stability balanced with fast dealing with, stable really feel, excellent manufacturing high quality and element, well-considered headset meeting, lifetime-warrantied bearings.
- Lows: Stiff seated trip, fiddly hose routing by the handlebar, blue backside bracket, washer on thru-axles can fall off throughout wheel removing.
Intentions of pace
The Ostro Gravel is a fairly clear instance of simply how shortly the game of gravel is progressing. It was barely two years in the past that Shrive advised the good thing about a completely aero gravel bike can be a fringe case, and so the corporate opted to deal with trip high quality and low weight with the design of the LS gravel bike (a mannequin that continues within the vary).
The rising professionalism of gravel racing has definitely swayed Issue to reassess this standpoint, however a rise in pace isn’t the one purpose. “Tyre measurement has come down a bit from the place the pattern was pointed,” stated Shrive in regards to the generally seen 38 and 40 mm tyres profitable races. At one level, it appeared like even wider rubber would take over in all aspects of gravel. In the meantime, current journey limitations gave the previous head of Cervelo’s engineering some free time to dive deep into analysis of tube shapes that also supply profit within the lower-velocity calls for of a gravel race bike.
“As quickly as you place a (body) tube behind a 40 mm tyre there’s actually nothing you are able to do in regards to the airflow, it’s simply going to be a large number,” stated Shrive about why Issue has as a substitute focussed on optimising tube shapes that sit in uninterrupted locations, particularly the handlebar, head tube, outsides of the fork, and the seatpost. These comparatively deep tube shapes characteristic truncated airfoil profiles tailor-made to make gradual speeds quicker (effectively, extra environment friendly).
The straightforward aim of those lower-velocity-focused tube shapes is to journey and re-curve passing air sooner. By doing so, Shrive stated, the airflow can then re-attach alongside the remainder of the tube for an extended interval and due to this fact create much less drag.
In the meantime, the opposite tubes, such because the down tube, mimic these used on the Ostro highway bike (though with out the concave shaping). Issue’s CEO, Rob Gitelis, famous that the tubes positioned in additional turbulent areas are already effectively optimised for a steadiness between weight and aero, no less than with a highway tyre in place. Equally, the considerably distinctive “converging nozzle” of the Ostro carries over to the gravel model, one thing Shrive notes will work as meant by conserving air shifting by the fork crown if the bike is used with highway tyres.
Sitting on the entrance of the bike, and stated to be one of many predominant pace benefactors, is a completely new one-piece handlebar and stem. Named the HB02, this carbon quantity is claimed to avoid wasting roughly 5-6 watts (at 48 km/h) in comparison with the unique built-in handlebar of the Ostro highway bike, and 9 W when in comparison with a conventional two-piece bar and stem. I’ll return to this bar shortly.
Definitely, Issue has put an entire lot of vitality into the general aerodynamic design of the Ostro Gravel, however the firm makes no particular claims about watts or seconds saved. All design iterations have been restricted to digital modelling (with a deep base of prior information). The corporate is booked in to validate its already-in-production design in a wind tunnel, however arguably such testing is probably going solely helpful for future iterations.
Within the meantime, Shrive speculated that with highway tyres fitted, the Ostro Gravel’s elevated tyre clearance and new handlebar are prone to greatest the road-focussed Ostro within the wind tunnel.
Energy and security
The information could not verify this, however it positive looks like product recollects have grown at the same charge to the quickly growing variety of hidden-cabled and one-piece-integrated bikes hitting the market. Issue itself had a public fail within the early days of the Ostro, and it’s nearly each day that I hear from riders who lack belief in these modern designs dominating new bike releases. And I really don’t blame such shopper hesitation, given the legally required security check requirements are lagging behind these fashionable built-in designs.
In discussing this subject with Shrive and Gitelis, I discovered that the corporate has taken its personal testing path to greatest perceive excessive failures that the prevailing ISO requirements don’t check for. And notably, Issue has been doing loaded influence testing on wholly constructed front-ends, together with the shifters/levers.
Shrive famous that he’s more and more attempting to vary the dialog round this testing away from a static load and one to vitality dissipation. “That is what we do with wheels, and we all know when the wheels will fail based mostly on a striker that predicts real-world outcomes,” Shrive stated. “So we began to use this to the remainder of the bike, impacting all of the totally different elements on the bike.”
And that brings me to the round-shaped steerer tube of the Ostro Gravel. It is a notable distinction from the Ostro highway bike, the place that steerer is flattened on its face with the intention to squeeze the cables down the entrance of a narrower head tube. In accordance with Gitelis, the design aim on the highway is all about minimising the frontal profile, and such a design will live on in future highway bike iterations.
In the meantime, the Ostro Gravel takes an easier path with an idea just like what the likes of FSA’s ACR and Deda’s DCR have already rolled out. It makes use of an outsized 1.5″ headset bearing high and backside, after which runs a typical 1 1/8″ spherical steerer inside it (the steerer tapers to 1.5″ for the underside bearing). Issue says the decrease velocity of gravel using permits for this wider form to not introduce an aero drawback. What wasn’t stated was that spherical steerers are doubtlessly higher suited to hammering throughout rocks and ruts for 200 miles (320 km) at a time.
Shifting to a typical outsized headset means the Ostro Gravel can be utilized with many different built-in headset and cockpit choices. Nonetheless, Issue (and sibling model Black Inc) provides its personal. This consists of the eye-wateringly costly self-lubricating stable polymer SLT bearings from CeramicSpeed. Issue combines that with its distinctive long-fibre-injected carbon fibre compression ring that contacts the carbon steerer with a clean and tall interface.
All informed, it’s a system that Gitelis suggests ought to resolve our frequent criticism of the problem round sustaining (or changing) bearings inside a hidden-cabled system.
From my standpoint, I agree that these SLT bearings will possible final the lifetime of the bike. Likewise, that uniquely lengthy compression ring offers me religion that steerer injury is unlikely (by reducing or materials despair). Nonetheless, some degree of upkeep, particularly cleansing and greasing the skin interfaces of the bearings, can be wanted ultimately. Fortunately, this gained’t require reducing brake hoses as long as the bike is about up with headset spacers and/or extra hose tucked inside.
Leaping again to the subject of energy, nothing on this bike feels flimsy or underbuilt for off-road use. Equally, the aero-profile tubes all really feel able to take a knock or two. To me, all of it looks like Issue has turned a web page and is producing bikes that will carry just a few extra grams, however in flip, will safely survive ongoing real-world utilization. And beneath the floor, the Ostro Gravel continues with Issue’s use of TeXtreme on the base layer, and boron as a reinforcement within the seatpost clamp space.
That’s to not say the Ostro Gravel is heavy, it’s simply evident that Issue isn’t attempting to stroll the tightrope between weight and reliability. The 54 cm painted body (as examined) weighs a decent 913 grams. At 490 grams (uncut), the fork isn’t on the sting. And it’s the same story for the 40 cm-wide (43 cm on the drops) one-piece handlebar/stem that is available in at 368 grams – about 60 grams greater than the Ostro highway bike. In the meantime, a 400 mm-length straight seatpost is a burly 262 grams, and you may really feel that there’s no compression within the materials when tightening the built-in seatpost wedge to its safe 8 Nm determine.
Geometry and match adjustment
The geometry of the Ostro Gravel is a contemporary mixture of efficiency race meets prolonged entrance centre, and it’s extra aggressive in each dealing with and match geometry when put next with the Issue LS gravel bike. There are six sizes, all of which characteristic lengthy attain figures and performance-minded-but-not-overly-aggressive stack heights. Like the opposite manufacturers doing comparable, the aim is to place you extra between the wheels, fairly than over them.
These seemingly scary attain figures are designed to be matched with barely shorter stem lengths and are additionally based mostly on the rising pattern of forward-slammed saddles. Issue is utilizing pretty steep seat angles to encourage a extra ahead place, however a alternative of both a straight or 20 mm-setback seatpost gained’t drive you into adapting to a brand new place. Although, as somebody with a cross-country mountain bike background who has long term a forward-positioned saddle, I’m all for the pattern. Additionally, I don’t doubt that folks used to procuring bike sizes based mostly on attain figures can be thrown an actual wobbly curve ball by the Ostro Gravel.
The one-piece HB02 handlebar is on the market in 20 mm increments starting from 360 to 440 mm (measured on the tops). Every handlebar grows by 15 mm both aspect on the drops because of the 7° flare which happens after the hoods (for instance, the 40 cm bar examined measures at 43 cm within the drops.) Issue then affords stem lengths starting from 80 mm to a surely-you-are-a-pro 140 mm size. And on high of that, Issue is at the moment finalising the design of an non-compulsory one-piece bar that may permit aero extensions to be fitted for all of the gravel rebels.
No matter measurement combo you select, the bars supply an 80 mm attain, a compact 120 mm drop, and a 3° backsweep. The form is fairly distinctive and affords extra greedy positions than ordinary. For instance, the highest’s lower nook helps you to relaxation your palms extra comfortably on the bend behind the hoods. And talking of these hoods, the rear-set clamping place was made to offset the longer attain quietly launched by present Shimano and SRAM hydraulic hoods.
One other neat element is that the flat aero profile occurs foward of the stem size. This implies you gained’t be hitting your knees on the bottom of the bar like I’ve complained about with another one-piece cockpits.
The wheelbase is definitely longer than a highway bike, however the steering geometry is effectively aligned to 1. Issue combines semi-steep head tubes angles with lengthy offset forks which end in some pretty fast path figures. In different phrases, the Ostro Gravel is quick-handling. Notably, these path figures stay roughly the identical all through the dimensions vary resulting from two totally different fork offsets getting used.
Issue’s reasoning for this fast dealing with relies on how tyre diameter immediately impacts the path determine. The smaller the tyre diameter, the shorter (and quicker) the path determine. The larger the tyre, the longer the path determine (slower dealing with). It’s an method that the likes of Trek have lengthy used and I’m glad to see it turn out to be more and more in style.
The Ostro Gravel affords a performance-road-bike-friendly 58 mm path determine with a 700 x 30 mm tyre fitted, whereas a 700 x 40 mm tyre sees that path determine lengthen to a still-quick 61 mm. Max out the 45 mm tyre clearance of the bike (which permits 4 mm of surrounding clearance) and your path determine can be 63 mm.
The underside bracket top is neither CX-tall nor Trek Domane low, with the rear-centre size rising by just a few millimetres because the sizes progress.
Meeting, half fitments, and bike choices
The Ostro Gravel makes no excuses for being an built-in bike with a number of proprietary options. The seatpost is exclusive to the body, and it’s held in by Issue’s built-in wedge clamp (one that’s straightforward sufficient to entry with frequent instruments).
Furthering the narrowed focus of this bike is a scarcity of fender and rack mounts – a typical omission on race bikes. You get provision for 2 bottle cages inside the entrance triangle, a spot beneath the entrance triangle, and mounts for a bento-style bag on the highest tube. And one tech element simply missed is that each one of these provisions aren’t your common aluminium rivnuts however are classier-looking flush mount rivnuts.
This gravel steed can solely be used with hydraulic disc brakes and digital gearing. The way in which the brake hoses are routed by the hole within the headset compression ring leaves no room for mechanical cables; frankly, such cables don’t belong anyplace close to a motorbike with wholly hid cabling like this.
That hid brake hose routing runs by Issue’s cut up headset spacers, into the stem, after which by the handlebar. The pinch level for me proved to be the fairly small exit holes on the handlebar, one thing that bent the ends of my magnetic inside cable-routing instruments and resulted in some naughty phrases. And I can guarantee you that these phrases would solely proceed if I’d wanted to additionally run Di2 wires out the identical holes.
I believe (hope) Issue will repair this ache level in future manufacturing runs, particularly because it makes swapping out a handlebar tougher than it ought to be.
Whereas a handlebar or stem size change would require re-routing these hoses, it’s far simpler to regulate stem top. Issue provides an aero preload topcap for a modern setup and a spherical topcap should you’re not sure in regards to the closing steerer size. For instance, I eliminated one of many aero cut up headset spacers from under the stem and ran common spherical 1 1/8″ headset spacers above whereas I dialled in my match. It’s a small element however is one thing that just a few in style built-in techniques don’t permit for.
One other small element is the equipped pc mount that bolts immediately into the entrance of the handlebar (there’s a canopy in place should you select to not use it). It affords an adjustable angle and Issue even provides a common adapter with the intention to add a light-weight, digital camera, or each. In accordance with Shrive, this pc mount was load examined with 800 grams on a wheel bump check for a hell of a very long time.
Trying to the underside bracket and Issue continues with T47 Asymmetrical, an offset iteration of T47 that I’ve but to see one other body producer undertake. The excellent news is that the threads match the T47 customary, the width between the bearings is regular, and common cranks match. In actuality, nothing stops you from operating any T47 Inner-style backside bracket after which utilizing just a few spacers on the driveside.
The higher information is that you just most likely gained’t even want to hunt out a backside bracket as Issue provides its bikes and framesets with a CeramicSpeed coated backside bracket together with the wanted covers and adapters to go well with 30 mm, DUB, and 24 mm spindle cranksets. And just like the SLT headset bearings, these backside bracket bearings additionally embrace a lifetime guarantee.
One other good contact with the underside bracket is the built-in backing to the instrument interface, which stops your chosen instrument from touching the paint when putting in or eradicating this backside bracket. That doesn’t sound like a lot, however Colnago C64s (and plenty of different bikes with skinny threaded backside bracket cups) are floating round with chipped paint as a result of the instrument butts up in opposition to the body. My solely criticism is that the underside bracket cups are anodised blue, and it’s pointless to attract a lot consideration to the bearings that sit between the crank. Issue, please make this half black.
In any other case, the remainder of the frameset is fairly regular. You possibly can run no matter highway or gravel wheels you would like. The body takes flat-mount brake calipers. And regardless of the chainstays not being dropped, there’s nonetheless loads of chainring clearance. For instance, you’ll be able to run as much as a 1x48T chainring if used on SRAM Vast or a 52/36T double crank with new Shimano 12-speed. There’s additionally a detachable entrance derailleur tab, with a alternative body cowl offered must you not run a entrance derailleur.
Already in manufacturing, Issue is providing the Ostro Gravel as a frameset for US$5,500 / €5,450 / £4,730, together with the headset, seatpost, backside bracket, and Black Inc cockpit. There’s a rolling frameset for US$7,500 / €7,430 / £6,450, which supplies you the frameset plus Black Inc’s first gravel wheelset. At 1,489 g paired, the Thirty-4 encompasses a 34 mm depth, 25 mm-wide hookless rims, and rolls on Black Inc’s hubs with CeramicSpeed Coated bearings hidden inside.
We then get to the whole bike possibility, all constructed with SRAM 1x or 2x groupsets and ranging from US$8,200 / €8,120 / £7,060 (SRAM Power AXS XPLR 1×12). I examined the near-top-tier full bike, decked out with full SRAM Crimson AXS XPLR 1×12, an influence meter, and Black Inc wheels. You possibly can anticipate to pay US$9,800 / €9,710 / £8,430 for this one.
My 54 cm pattern weighed 8.05 kg (17.74 lb), with out pedals or bottle cages, however with a wholesome dose of tyre sealant within the 40 mm Goodyear tyres.
Relying on the place you reside, Issue Bikes are both offered by a retailer, otherwise you deal immediately with the producer. In the event you’re in Australia, the UK, or the USA, you’ll possible be coping with Issue direct. And whereas the Ostro Gravel is much from being an inexpensive bike, the inclusion of high-end bearings and some added extras affords some worth in comparison with Trek, Specialised, Pinarello, and so forth.
There’s a alternative of two colors: a matte and uncooked “Bare Grunge” (as examined) and “White Grunge”. The White Grunge will possible carry an approximate 50 g weight penalty.
The Ostro Gravel as a gravel bike
Lastly, I get to how the Ostro Gravel rides. And if I have been to select a single phrase to explain it, that phrase can be ‘stiff’.
It’s a rewarding feeling on the highway and even hammering up a well-kept grime highway. The bike responds with out hesitation, and there’s no vagueness between your hips and the wheels. In some ways, the Ostro Gravel responds like a top-level highway bike. Nonetheless, the apparent draw back is that no matter vibrations, bumps, or impacts the tyres don’t soak up, your legs or ass will.
To return to an earlier a part of this evaluate, this can be a limitation and a trade-off of the slippery aero shapes that have been examined to take a beating. “Whenever you get aero sections and also you elevate the check requirements up like we’ve got for gravel bikes, you begin to get actually rattling stiff shapes attempting to withstand these masses as the form doesn’t lend itself to deflect,” stated Shrive, all of the whereas suggesting that they anticipate a lot of the bike’s trip consolation to come back from the tyres.
The consolation from excessive quantity tyres is one thing that many bike manufacturers depend on, and whereas the tyre system stands out as the most effective spring system in a inflexible bike, it has its limits. With broad tubeless tyres run on modern-width rims at low pressures, the bounds will preserve you remoted from decently tough terrain. Nonetheless, these limits finish when the bottom is plagued by square-edge bumps, depressions within the floor, and relentless vibrations. And in these tough conditions, the stiffness of the Black Inc wheels solely enhance the suggestions felt.
We generally complain about inflexible gravel bikes being unbalanced entrance to rear. It’s comparatively straightforward to make a seatpost versatile for consolation, however so usually it’s rarer to discover a front-end that’s equal in consolation. Oddly sufficient, I discovered the Ostro Gravel to be the reverse, with the one-piece handlebar flexing simply sufficient to really feel extra muted. In the meantime, that deep part and stiff seatpost affords little consolation from what the rear wheel fails to silence. The result’s a motorbike that retains your arms extra comfy and means that you can simply keep in management. Nonetheless, staying seated by the identical sections feels fatiguing for the remainder of the physique.
Definitely, larger tyres will assist to offset this stiff trip, and if it have been my very own I’d be placing in some tyre inserts to get essentially the most out of the obtainable tyre quantity. That stated, there’s little else you’ll have the ability to do with getting extra consolation from this bike because the seatpost can’t be switched out for one thing extra versatile.
The bike’s stiffness definitely shines by when taking part in a sport of under-biking. And whereas the front-centre size is prolonged, it’s not fairly lengthy sufficient to wholly keep away from toe overlap (no less than within the 54 cm measurement) in awkward technical circumstances.
It’s totally different when going flat-out on highway and even family-car-friendly gravel roads. Right here the tyres do loads, whereas the longer wheelbase provides a wholesome quantity of stability and management. Such stability usually comes on the expense of a motorbike’s potential to react shortly, however that merely isn’t the case right here and it’s straightforward to regulate the path of the Ostro Gravel.
The match geometry of the Ostro Gravel is certain to go away many riders second-guessing what’s greatest for them. At 170 cm (ish) I may have gone with both a 52 or 54 cm measurement. I opted for the bigger with a shorter stem (90 mm) and narrower bar (400 mm). It definitely looks like a efficiency bike, however neither the attain nor stack are problematic for my at the moment poor flexibility.
One-piece handlebars can usually make or break an in any other case good bike, and Issue has executed its analysis right here. Irrespective of the place I positioned my arms alongside or across the bar, they all the time felt at residence.The beneficiant high floor offers you management with solely a light-weight maintain, whereas the flare on the drops is sufficient to add loads of wrist clearance with out feeling such as you’re holding onto a wholly totally different handlebar.
The Ostro Gravel as a highway bike
Issue didn’t simply design the Ostro Gravel to race gravel; it was constructed figuring out that many will wish to use it as a highway bike, too. And Issue surprisingly took the additional step of placing it by the UCI approval for highway race use.
As talked about earlier than, going to a highway tyre has a direct influence on the dealing with of the bike and, certainly, the Ostro Gravel turns into extra darty even with an all-road-friendly 32 mm tyre fitted. Right here it barely takes a twitch to get the entrance wheel to dive right into a nook, and the slower you go the extra noticeable such twitchiness turns into.
Nonetheless, altering to highway tyres on the Ostro Gravel doesn’t fairly rework it into the highway racing machine you would possibly hope for. With its prolonged entrance centre, the geometry weirded me out.
I used to be wanting down at what appeared like a completely aero highway race bike, which steered like a race bike, and which had stiff trip high quality like an aero race bike, and but, the entrance wheel was noticeably additional out in entrance of me. I discovered myself having to appropriate for this, getting my weight extra over the entrance of the bike for sharp corners. Gradual climbs would reveal a sense akin to a head tube that’s too slack (regardless that it isn’t) – a way of wheel flop if you’ll.
Now none of that might cease me from utilizing and having fun with the Ostro Gravel as a highway bike. It additionally wouldn’t gradual me down or maintain me again in hanging in a gaggle trip or racing mid-pack in a membership race. But it surely’s nonetheless essential to notice that the attract of the unicorn race bike that’s as comfy being a focussed highway bike as a gravel shredder isn’t a actuality – there are all the time trade-offs.
Furthering these compromises is the fairly blatant situation of gearing. The 44T entrance chainring matched with the 10-44T XPLR cassette had me trying to find a neater gear when using free, rocky, and 20%-gradient off-road inclines. In the meantime, swap the tyre to a road-friendly measurement and all of the sudden you’re left trying to find a tougher gear.
Sadly there’s no straightforward reply to this drawback, however the answer most likely includes a entrance derailleur – one thing that Issue does supply inside its bike construct choices.
To play the position of egocentric author for a second, my private dropbar bike journey has introduced me to need a quick and lightweight gravel bike that I can predominately go away in highway mode with a special set of wheels. The Ostro Gravel is the bike I’ve been searching for in so some ways. And but, a lot of my native gravel errs to the aspect of wildly tough and technical, and because of this, the Ostro’s built-in method and highway race bike stiffness simply aren’t ideally suited to those under-biking wishes.
Whereas it doesn’t go well with my localised wants, there are certainly many riders on the market in search of a do-it-all dropbar steed for using on the rivet throughout poorly stored sealed roads and better-kept grime roads. And the Ostro Gravel is definitely a worthy contender for such riders.
Past the stiff trip high quality, maybe the one remaining sticking level is the shortage of quantitative knowledge for what a non-professional rider could achieve from the aero design method. I’d wish to know that I’m saving quantity of vitality in my legs to beat the elevated fatigue of the stiff construction.
In fact, like something, that reply will all the time rely on the day’s state of affairs. A smoother gravel course will see quicker speeds and fewer vibration fatigue on the physique; circumstances the place the Ostro Gravel is prone to shine. In the meantime, on a tortuous course, and due to this fact at slower speeds, I’m not fairly satisfied the Ostro Gravel would be the quickest bike of the day.
Issue is neither the primary to carry aero to gravel nor will it’s the final. The marketplace for road-bike-lookalike gravel race steeds is a fast-growing one, and it’s due to the flexibility of such bikes.